1. Field of the Invention
This invention pertains to processing thin sheets of material, and more particularly to apparatus that feeds, processes, and stores large numbers of individual or sets of thin sheets.
2. Description of the Prior Art
Numerous types of equipment have been developed to process sheets of paper. For example, machines for feeding, folding, and sealing paper sheets are well known and in widespread use.
Some prior machines combine the functions of folding and sealing paper sheets. Representative combination folding and sealing machines may be seen in U.S. Pat. Nos. 6,080,251; 6,080,259; 6,086,698; and 6,264,592. Typical mechanisms for feeding paper sheets are shown in U.S. Pat. Nos. 4,394,009; 5,246,221; and 6,145,831. U.S. Pat. No. 6,554,271 discloses a gate tip paper feeder that may be used with a paper folding machine.
Most prior sheet processing equipment was limited to handling only one sheet at a time. Although there have been exceptions, in general considerable effort was expended in the past to prevent more than one sheet from feeding at a time, because feeding multiple sheets was likely to cause jams downstream. In some equipment, a supply stack of multiple sheets was loaded at an in-feed station, but only one sheet at a time was removed from the stack for being propelled downstream for processing. In other equipment, the sheets were supplied individually from a source such as a printer to a downstream station for further processing.
In many situations it is desireable to fold two or more sheets together as a single set. Most prior folding equipment was not capable of performing that function, because, as mentioned, the feeding devices of the prior machines could not feed more than one sheet at a time, so there was no way to propel multiple sheets together to the folding mechanism. One prior machine was capable of folding more than one sheet at a time as a set. That machine was limited to folding sheets that were fed by hand to the folding mechanism, however. It was not capable of feeding sheets one at a time from a supply stack or other equipment to the folding mechanism.
Another problem with prior sheet feeding and folding machines was that they could not hold all the folded sheets that came from a supply stack. The machines normally included an output tray that held the folded sheets. However, the tray was too small to hold the number of folded sheets equal to the capacity of the machine at the supply stack. Consequently, an operator had to be present and remove the folded sheets from the output tray. Otherwise the folded sheets would spill off the output tray onto the floor.
Thus, a need exists for a way to process multiple sheets simultaneously, as well as for other improvements to sheet processing equipment.